1. Field of the Invention
This invention is directed to an apparatus for producing quality fire retardant cellulose insulation and is more particularly directed to a system and process for grinding and thoroughly mixing chemicals with the cellulose product to obtain a fire retardant, quality insulation material.
2. The Prior Art
The applicant hereby lists the most pertinent prior art of which he is aware:
U.S. Pat. No. 2,100,848; PA1 U.S. Pat. No. 2,428,100; PA1 U.S. Pat. No. 2,707,690; PA1 U.S. Pat. No. 2,707,847; PA1 U.S. Pat. No. 2,973,740; PA1 U.S. Pat. No. 3,013,525; PA1 U.S. Pat. No. 3,118,459; PA1 U.S. Pat. No. 3,548,782; PA1 U.S. Pat. No. 3,967,005.
The Soulen patent (U.S. Pat. No. 2,428,100) is directed to a single stage machine for making cellulose insulation material from waste paper and the addition of a chemical fire retardant substance to the material during the grinding process. The Anliker patent (U.S. Pat. No. 2,707,847) produces rockwool fiber insulation and uses a spray nozzle which sprays an additive in the direction of the fiber travel for thoroughly coating these fibers. The patent to Hardgrove (U.S. Pat. No. 2,100,848) shows a feeder control mechanism for controlling the amount of material introduced into a pulverizer so that the amount of material will not overload the capacity of the pulverizer. This patent also teaches the use of a cyclone or conical separator to separate fine or small particles from coarse material. The Cattaneo patent (U.S. Pat. No. 3,967,005) shows an auger type conveyor for moving a quantity of pellets and adding liquid and dry materials to the pellets for coating and mixing as seen in FIG. 4.
The patents to Fuller (U.S. Pat. No. 3,013,525), Hopkins (U.S. Pat. No. 2,973,740), Pearson (U.S. Pat. No. 2,707,690), Stumpf (U.S. Pat. No. 3,118,459), Bergquist (U.S. Pat. No. 3,548,782), and Wiegand (U.S. Pat. No. 3,622,077) show various arrangements for adding liquid materials by means of spray nozzles to a flow stream of primarily fibrous or light materials. The Fuller and Hopkins patents teach the use of a deflector in the center portion of the stream and the angular spraying of the liquid additive across the direction of flow of the materials. Stumpf shows the changing of the velocity of the materials and the spraying of the additive into an area of low velocity. Pearson, Bergquist, and Wiegand show various arrangements for spraying additives into the flow stream of materials. The Fuller patent (U.S. Pat. No. 2,808,580) is typical of the flow meter alarm systems which use light and photoelectric devices for detecting variations in flow quantity. FIG. 2 shows the use of the flow meter with an alarm system and/or control valves for controlling the amount of flow within the system.
In the past, it has been common practice to produce cellulose insulation by merely shredding or grinding ordinary paper stock, newspapers, or waste paper in various types of grinders of the hammer, ball, or shredding types. Because of the highly flammable character of the shredded paper material which produces the cellulose insulation, it is a mandatory requirement that some type of fire retarding qualities be added to the insulation. Usually during the shredding or grinding process, dry chemicals for fire proofing or retarding the insulation material are added. The addition of the dry chemicals directly into the grinder performs a reasonable mixing of the materials to provide the desired characteristics.
One of the major problems that have been found in the prior art systems is that the dry chemicals are ground and powdered along with the cellulose material which makes the chemicals subject to producing a dust-like condition which allows light air currents to easily disperse the chemicals and reduce the fire retardant character. In addition, major problems have been encountered in controlling the flow of dry chemicals to the grinders to maintain the proper ratio of relatively expensive chemicals to the paper cellulose materials. As can be expected, there is an optimum ratio of chemicals to insulation material to provide the optimum fire retarding results. In the past, there have been numerous unsuccessful attempts to mechanically control the quantity of chemicals being introduced into the grinder in direct relationship to the amount of paper being fed or delivered to the grinder.
Other processes have tried to spray a liquid chemical into the material, but this has been found to be relatively difficult in that uneven and inconsistent wetting of the materials results, producing a product which has varying degrees of fire retardant capabilities provided in the finished product. In addition, overwetting of the cellulose insulation material produces a gummy and sticky mass which is extremely difficult to transport and convey during the process. Thus, using the liquid spray technique causes enumerable difficulties in maintaining a continuous production with the necessity for frequent shut-down for the cleaning of pipes and conduits.
Another major problem that has been in constant occurrence in the insulation industry is the control and bagging of the insulation product to provide optimum packing and filling of the product containers and ease in handling the material. In many cases a sack or bag has been held over the bottom end of a chute with the material dropped by gravity through the opening until the bag appeared to be relatively full. Very little density control and materials consistency was possible with this type of arrangement.
In addition, various mechanical control systems, including hydraulic and pneumatic, have been proposed for insulation producing aparatus in the past. Various types of automatic electronic controls have also been suggested but it has been found that these systems are inadequate and unsatisfactory in providing a quality insulation material that is so vitally needed by the public in these times of short energy supply.
As mentioned above, the traditional method for fire-proofing cellulose insulation material has been the dry method which involves the addition of certain dry granular chemicals to the paper stock as it enters the grinders. The dry, powder-like chemicals are thus mixed and ground with the paper material to form a fire-retardant insulation consisting of about 20% by weight of chemicals and 80% paper. A common criticism of this product is that it is very dusty, especially when it is blown into attics and other spaces to be insulated. Other criticism of this manufacturing process includes an uneven ratio of chemicals to paper and the possibility of settling out or separation of the chemicals from the paper at some later time. Thus, the most common criticisms or weaknesses in the prior art methods of manufacturing cellulose insulation have been the dusty nature of the final product, the possible separation of the dry fire retardant chemicals from the paper, and the unreliable method of mixing the correct ratios of chemicals and paper.